1. Field of the Invention
The present invention relates to devices for applying strips of material to a surface, and in one aspect to devices for applying strips of reflex-light reflective material around tire casings.
2. Description of the Prior Art
Tires including reflex-light reflective strips around their sidewalls (as taught in U.S. Pat. No. 2,382,908) have found particular acceptance for use on bicycles and motorcycles to provide a measure of safety when the cycle is operated after dark. Such tires are typically constructed by adhering parallel strips of an uncured elastomer (such as neoprene rubber) supporting a layer of reflex-reflective elements to the solvent tackified adhesive coated outer surface of an unvulcanized tire casing. The tire casing is then vulcanized in a tire mold to form a completed tire having a U-shaped cross section with tread, embossed brand and size information and the strips permanently incorporated in its sidewalls.
A known prior art device for applying such strip material to an unvulcanized tire casing is the device illustrated in Drawing No. TR-175 which is available from the Special Enterprises Department of Minnesota Mining and Manufacturing Company, Saint Paul, Minn. This device includes two parallel head assemblies each manually movable into engagement with a casing at a fixed applying station defined along means for rotating the tire casing (e.g. a tire building wheel). These head assemblies each include fixed guide means which defines a path for a length of the strip material from a supply reel to the periphery of an applying wheel, and means along the path for separating a protective liner from the strip material. A partial vacuum is provided in openings around the periphery of the applying wheel to support an end of the strip material thereon when the head is not at the applying station. When the head is manually moved to the applying station, the applying wheel presses and adheres the strip material against the tire casing so that movement of the tire casing pulls the strip from the supply roll and applies it around the casing.
While this device is serviceable, it does not provide means for regulating the amount of stretch in the applied strip material so that the stretch in the strip material can be matched to the stretch in the tire casing at the point of application. For examples of this problem, if such stretching exceeds 3 to 5 percent when the strip material is applied to a tire casing on a circular tire building wheel it can cause partial release of the reflex-reflective material and cracking of the strip material when the tire casing is vulcanized. When the strip material is applied to a tire casing on the periphery of one pulley in the "Mono-Band" type of tire builder having spaced pulleys between which the tire casing is tensioned in the manner of a drive belt, the stretch may need to be in the range of 10 to 15 percent or higher. If it is too low, spaced lengths of the applied strip material will pop away from the tire casing and form projecting loops after the tire casing is removed from the pulleys.
Also an operator using the aforementioned device has to manually sever the strip material after it is applied around a tire casing, so that obtaining a desired relative position between the ends of the applied strip is time consuming, tedious, and highly dependent on the care taken by the operator.